;Waits for multiple top-level or child windows.;At first call an AddX function to define windows to wait for. Call it for each window.;Then call a WaitX function to wait for a condition.

;This is common to all WaitX functions:;;;;Return 1-based index of the added window that satisfies the wait condition.;;;;Succeed if the condition is true when called.;;;;Use opt waitmsg and opt hidden.